It is well-known that durable structures such as concrete structures, brick structures or rocks can be demolished by utilizing an explosive material, for example, dynamite, which has an excellent demolishing effect. However, the use of explosive material presents an environmental problem due to the generation of a tremendous explosive noise, vibration, and shock and the scattering of dust and stones, and furthermore it is always dangerous.
Also, it is well-known that durable structures can be demolished by means of mechanical methods using an impact steel ball, a rock drill or a pick hammer. However, the mechanical methods exhibit a relatively small demolition effect and usually generate tremendous noise and vibration.
Various attempts have been made to remove the above-mentioned disadvantages of the conventional explosive and mechanical methods by utilizing an expansible material. In the attempts, a necessary number of holes were formed in a durable structure and were filled with an aqueous slurry of an expansible material so as to allow the expansible material in the holes to hydrate and to create a large expanding force. In a most typical example, the expanding force can be created by the hydrating reaction of quick lime.
The quick lime expansion method is advantageous in that no noise, vibration or shock is produced by the demolition process, except for noise produced when the holes are formed in the durable structure by means of a drilling procedure. Also, the quick lime expansion method is not dangerous.
However, the quick lime expansion method is disadvantageous in that the hydrating reaction of the quick lime takes place extremely rapidly. As soon as the quick lime is mixed with water, the hydration of the quick lime is carried out and the mixture expands rapidly. This rapid hydration of the quick lime results in a rapid increase in the viscosity of the mixture and, therefore, in a difficulty in pouring the mixture into the holes formed in the durable structure to be demolished. Even if the mixture could be poured into the holes, the mixture would immediately spring out of the holes due to the rapid expansion thereof. In this case, the expanding pressure generated by the mixture cannot be utilized to demolish a durable structure.
Various attempts have been made to remove the disadvantages of the conventional quick lime expansion method. For example, in the demolition method disclosed in Japanese Patent Application Laid-open No. 51-128131 (1976), the upper openings of holes formed in a durable structure are sealed with lids which are firmly fixed to the durable structure. This method is effective for preventing the springing out of the quick lime aqueous slurry. However, it is disadvantageous in that the procedure for fixing the lids to the durable structure requires much time and labor and is costly.
In a method disclosed in Japanese Patent Application Publication Nos. 47-40692 (1972), 50-869 (1975) and 50-7372 (1975), a hydration-retarding agent comprising a silico-fluoride compound is added to the quick lime aqueous slurry. In this method, it is difficult to adequately control the addition of the hydration-retarding agent on the basis of the hydrating property of the quick lime used.
In the demolition facilitaing agent disclosed in Japanese Patent Application Laid-open No. 55-142894 (1980), CaO crystals are coated with 3CaO.SiO.sub.2 crystals in order to control the hydration rate of the CaO crystals. In this agent, since the content of CaO crystals in this agent is relatively small, the expansion pressure produced by the hydration of this agent is not very large. Also, this agent is disadvantageous in that when the clinker is produced from raw materials at an elevated sintering temperature, CaSO.sub.4 contained in the raw materials is heat-decomposed so as to generate undesirable SO.sub.2 gas.
The inventors of the present invention have carried out a large amount of research on the relationship between the expansion pressure created by a demolition-facilitating material and the demolition effect of the agent on a durable structure, for example, a concrete structure or rock. As a result of this research, the inventors found that when the expansion pressure produced by the demolition-facilitating agent is about 30 kg/cm.sup.2 or more, it is possible to make cracks in the durable structure. Also, when the expansion pressure is 200 kg/cm.sup.2 or more, it is possible to satisfactorily demolish the durable structure. That is, the demolishing effect can be increased by increasing the expansion pressure generated by the demolition-facilitating agent.
In consideration of the above-mentioned facts, the inventors of the present invention eagerly carried out research concerning a new type of demolition-facilitating agent which is capable of producing a large expansion pressure when it is brought into contact with water which exhibits a great demolition effect in the case of various durable structures and which is free from the disadvantages of the conventional demolition-facilitating materials.